Mercury-pump system



E. B. SHAND MERCURY PUMP SYSTEM 2 Sheets-Sheet vl Filed Aug. 5, 1927Feb. 19, 1929. Y

|NvENToR ATTORNEY Feb. 19, 1929.

i E. B. SHAND MERCURY PUMP SYSTEM 2 Sheets-Sheet Filed Aug. 5, 192777mg` in Hinufes.

xNvEMToR 63 Erfo/ 5. SMI/7d.

E P No.

s o on n ATTORNEY Patented Feb. 19, 1929.

UNITED sTATEs REBOL B. SHAJID, I PITTSBURGH, PENNSYLVANIA, ASBIGIOB T0mGHOUlI ELECTBIO IANUIAGTUBUG (mm, A CORPORATION 0I mmvm HEBCUBY-TUIP umApplication ma Annu a, iss?. semi l. non.

My invention relates to vacuum pumping systems and it has particularrelation to suc systems as applied to metal-tank mercury-arc rectifiers.

5 rlhe principal object of my invention is to provide means forcontrolling the action of the high-vacuum mercury-vapor pump andamotor-operated valve which connects said pump to the rectifier tank tobe evacuated.

A more particular object of my invention is to provide a novelvalve-operating mechanism for providing' a rapid closure of the valve,when occasion demands, and. a more leisurely opening thereof at propertimes.

A further object of my invention is to provide a novel thermostaticcontrol means associated with the mercury-vapor pum for opening andclosing the valw of the a ovedescribed combination at the proper times.

A still further object of my invention is to provide a novel water-flowrelay which is associated with the cooling circuit of the mercury-vaporpump for controlling the heating circuit thereof, so that the heatingcircuit may be energized only when the proper amount of cooling water isbeing circulated.

`With the foregoing and other objects in view, which will be understoodfrom the f'ollowing description and claims, my invention consists in the`combinations and details of structure herein described and claimed andillustrated in the accompanying drawing', wherein Figure 1 is a curvechart illustrating the conditions inthe water-flow meter,

Fig. 2 is a partially diagrammatic crosssectional view illustrating theentire assembly and the electrical circuits associated therewith,

Fig. 3 is a curve chart referring to the operation of the thermostaticdevice on the mercury-vapor pump,

Fig. 4 is an elevational view'of a part of the valve-operatingmechanism, and

Fig. 5 is a plan view, partially in section, illustrating the worm shaftand its connection to the motor shaft.

As shown in Fig. 2, my invention is preferably applied to a metal-tankrectifier 7, which is shown on a somewhat reduced scale,

as compared to the scale on which the other cation, Serial No. 141,783,filed October 15. 1926, and issued November 27, 1928, as Patent1,693,407. The valve is of the movingdiaphragm type, having a diaphrawhich is secured a valve seat 1-1 an a valve stem 12.

The valve 9 is connected, in turn, to a mercury-vapor pump 13 of anydesired construction, having an exhaust port 14 which is connectedtoaninterstage reservoir and rotary pump, neither of which is illustrated,as any mown or preferred form of apparatus may be utilized for thepurpose. The mercu pump 13 is provided with a water acket 15 having aninlet port 16 in which is located a feeding valve 17 for controlling thewaterflow to a predetermined restricted amount and pressure, a suitablesource of water supply (rligt shown) being connected to the inlet pi e nthe discharge pipe'18 for the water, as

it leaves the jacket surrounding the pump,

is provided a water meter 20, or mechanism for responding to pressureswhich are developed as a result of the flow of water therethrough. Thewater meter 20 is shown somewhat diagi'ammatically in Fig. 2 forsimplicity of illustration, but the essential features of the mechanismare well illustrated. The device consists of a pressure chamber 21, onewall of which consists of a movable diaphragm or bellows 22, to which isconnected the stem 23 of an electrical switch mechanism 24, for apurpose hereinafter described. The pressure chamber 21 is in directcommunication with an inlet port 25 of the water meter and is incommunication with an outlet port 26 by means of a restricted orifice27.

In the operation of the cooling-water mechanism, it will be understoodthat a relatively high-pressure source of water ysupply is Connected tothe intake pipe 16, wherein the water pressure may be as much as 50pounds per square inch, or more. A restricted amount of water iscirculated throu h the. cooler, as controlled by the feeding va ve 17,leaving through the meter 20, the outlet port 26 and the discharge pipe18. The restricted water flow, passing through the water meter and theoutlet passage 26 of the meter, said opening being normally closed bymeans of a plu or closure member 30 depending from the iaphragm 22. Whena certain predetermined pressure is developed against the diaphragm 22,the switch contacts 24 are closed, and at, or just beyond, thispressure, the plunger 30 comes out of the opening 29, therebv providingasfrelatively unrestricted flow of water through the meter, so thatexcessive pressuresare not developed in the pressure chamber 21.

The operation of the water-flow meter is illustrated in Fi 1, whereinthe full-line curve indicates t e relation which exists between thepressure in the pressure chamber 21 and the rate offlow of the waterpassing through the meter. It will be noted, that, at the normal orexpected rate of water flow, as controlled by the valve 17 and indicatedat 32 in Fig. 1, the flow of the water through the meter at a restrictedrate develops a pressure of five pounds per square inch in the pressurechamber, which is only one-tenth of the pressure in the water supplymain 16. However, if the water flow increases to a value just beyond thepoint 32, as indicated at 33, the bypass passage 29 opens and thesensitivity of the meter changes abruptly, as indicated by thedifference in the slopes of the lines 34 and 35 of the curve. The dottedline 36 indicates the rapid rise in pressure which would be obtained ifthe by-pass passage 29 were not provided.

The mercury-vapor pump 13 is also provided with an electric heatingelement 38 and with aA thermostatic contacter device 39 of any desiredconstruction, said thermostat element being placed in any one of severaleffective positions, whereby it responds to temperature conditions witin the pump and gives a reliable indication of the operativeness of thepump.

The operation of the pump is indicated 'by the curves shown in Fig. 3.When the heating element 38 is first energized, it takes the pump aboutthree-quarters of an hour to heat up to the point wherein it willoperate against the pressure of the order of from 1 to 5 or 10millimeters of mercury existing in the eX- haust pipe 14 of the pump,which is connected to the interstage reservoir (not shown). The vacuumvalve 9 must remain closed all during said time-interval while the pumis heating. To provide a timedelay switch, which would ive satisfactoryoperation at such extremely ong time delays,

would be very costly and unsatisfactory from other considerations.Heretofore, it has been necessary to provide intricate and not altoethersatisfactor high-vacuum measuring evices in the inta e passage of themercur vapor pump, or, more commonly, to do wit out the-protection ofany such devices. In my device, by the simple expedient of utilizing athermal-.responsive contacter 39, I have provided a simple expedient forrespondmg accurately to the operative condition of the pump.

In Fig. 3, the heating and cooling curves of the pump are shown,indicating the relations existing between the temperature at thethermostat 39 and the time in minutes after the energization ordeenergization of the heating element 38. If the pump begins to beoperative at a point 42 on the heating curve 43, the thermostat 39 isset to close its contacts at a slightly higher temperature, whereby acircuit 44 is energized for actuating the operating mechanism of thevacuum-pump 9, as .will be subsequently described. If, during thecooling of the pump after the deenergization of the heating means 38,the pump begins to become ineffective at the point 45 of the coolingcurve 46, the thermostatic contacts 39 are opened at a somewhat highertemperature, so that the vacuum-valve 9 will be altogether closed beforethe critical temperature 45 is reached, or, more commonly, the controlcircuit 44 will be opened as soon as the heater circuit is deenergized,as will be subsequently described.

The valve-operating mechanism consists of I a pivotally mountedsegmental member 47 having a cam surface 48 of var ing radii, forpressing against the top of tie valve stem 12 in order to close thevalve against the actionof a spring 49 surrounding the valve stem. Thesegmental cam member 47 is ieldably pressed in a valve-closing directiony means of a spring 50, whereby the valve is normally held tightlyclosed, except when means are provided for opening the same and holdingit open.

The valve-opening means consists of a segmental worm-gear member 51,Which is mounted on the cam shaft 52, and which is driven by a pivotallymounted worm shaft 53 which carries a worm 54 and which is pivotallymounted at one end to oscillate around a motor shaft 55, to which theworm shaft 53 is connected by means of a bevel gear 56, the motor shaft55 being driven by an electric motor 57. It will thus be evident thatthe driving shaft 55 of the motor is parallel to the cam shaft 52, andthat the worm shaft 53 is at right angles to the motor shaft and ismovable so that the worm 54 moves into and out of engagement with theworm-gear segment 51.

The worm shaft 53 normally falls to a position out of engagement withthe segmental ar 51 and is adapted to be moved into meshmg engagementtherewith by means of an electromagnet 58 which-is energized from thecontrol circuit 44 leading from the thermostatic contactor 39hereinabove described. The motor 57 is also energized from the controlcircuit 44, but through the mediation of a limit switch 59 in the shapeof a contactor segment carried by the segmental members 47 and 51 andhaving a dead spot or insulated portion 60 which opens a circuit of themotor 57 when the valve is in its fully opened position, as indicated inthe drawlngs.

The operation of my apparatus will now be readily understood. As long asthere is no water flowing in the cooling circuit of the mercury pump 13,or if the water-flow 1s not suilicient'to develop five ounds pressure inthe water-flow meter'20, t e electrical switch 24, associated therewith,is open and no part of my apparatus may be energized. The yworm 54 istherefore out of Contact with the ear segment 51 and the valve is drawnand held to its closed position by means of the spring 50 pulling on thecam segment 47. The pump heater 38 is also deenergized so that the pumpcannot be ruined by operation without any cooling water.

When the pro er amount of cooling water flows through the water-flowrelay 20, the switch cont-acts 24 are closed, thereby energizing thepump heater 38 from a suitable supply line such as the 11G-volt rline61. After a certain interval, which is indicated in Fig. 3 as beingabout 45 minutes, when the mercury-vapor pump 13 is inV an operativecondition, the thermostatic switch-contacts 39 close, thereby energizinthe control circuit 44 which energizes t e electromagnet 58 and alsoinitiates the movement of the motor 57, it being noted that the camswitch 59 is in the dotted-line position indicated in Fig. 2 when thevalve is closed, so that the dead point 60 is not under the stationarycontacter associated therewith. The energization of the electromagnet 58draws the worm 54 into engagement with the wormgear segment 51 and therotation of the motor 57 drives the worm in a direction such as to openthe valve 9, moving the cam segment 47 against the tension of theclosing sprlng 50.

When the valve is fully opened, the dead point 60 of the segmentalswitch 59 open-circuits the motor 57, but the electromagnet 58 remainsenergized, so that the segmental members are prevented from moving backto switch-closing position by means of the worm 54 which is anon-reversible gear mechanism.

The electromagnet 58 remains energized as long as t-he mercury-vaporpump 13 is in an operative condition. Upon failure of the cooling-wa-tercircuit, the switch 24 opens, thereby deenergizing the control circuit44 ofthe electromagnet 58, whereupon thel worm 'cuit 44 would still beopen-circuited 54 immediately drops out of engagement with the gearsegment 51 and the closing spring 50 instantaneously closes the vacuumvalve 9 with a snap action, so that the `vacuum valve is fully closedbefore the mercury-vapor ump becomes inoperative at the point 45 in ig.3, indicated as bein someten minutes later. If the heater 38 s iouldburn out while the water-relay 24 is still closed, the control cirb -thcthermostat 39 before the pump had cooled to the critical point 45 in Fig3, as hereinabove described.

In the particular embodiment of my iuvention shown in the drawing, Ihave contemplated that the mercury-vapor pump shall be normally workingall the time, intermittent pumping action being obtained by thelntennittent action of the rotary pump (not shown) to pump out theinterstage reservoir (not shown) when its pressure becomes too great, asset forth in a copending application of Vladimir K. Zworykin and myself,filed Aug. 3, 1927, Serial No. 210,275.

Referring now to the structural detailsshown in Fig. 4, I preferablyprovide a compression spring 62 for positively actuating the worm shaft53 toward its disengaged position. The lower end of the spring bearsagainst a. horizontal flange 63 on the bearing member 64 which supports'the Worm shaft 53, and the upper end of the spring bears against a nut65 on a link member 66 passing through the compression spring 62 andalso through a perforation 67 in the iiange or shoulder member 63.

The upper end of the link member 66 is pivotally supported at 68 fromthe segmental members 47 and 51 in such manner that when the valve is inits fully open position, as indicated by full lines on the drawing, thespring 62 is tightly compressed so that the Worm shaft 53 is stronglypressed toward its unmeshed position, whereas, when the valve is closed,as indicated by dotted lines, the pivotal point 68 is moved upwardly sothat the pressure of the compression spring is very much reduced, thepressure being preferably entirely removed and the spring being idle inthe closed position of the valve.

The object of the construction just described is to facilitate theoperation of the electromagnet 58, which pulls upon an extension arm 69of the frame 64 supporting the worm shaft 53, the magnet armature beingso pivoted that it presses upwardly on the extension arm 69 when the manet is enerized. As the pulling force o the magnet 1s much less at thebeginning of the movement of its armature than at the end, the reducedpressure of the compression spring 52 makes it possible to utilize asmaller magnet 58 than would otherwise be necessary, and yet theincreased compression of the lll) spring 62 in the final open positionof the valve is. not suicient to overcome the pull of the magnet on itsarmature when the magnet is in its fully closed position as indicated infull lines on the drawing. i

While I have described my invention in a referred embodiment, I do notwish to be imited altogether thereto, as many changes will occur tothose skilled in the art, whereby the essential advanta es of minvention may be incorporated in s i htly iiferent apparatus. Idesire,there ore, that the description and drawings be considered asillustrative only, and that the appended claims shall be given thebroadest construction consistent with their language and the prior art.

I claim as my invention:

41. In a vacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heating means .for said pump, meansfor circulating a 'cooling fluid around said pump, pipe connectionsincluding a valve between said chamber and said pump, mechanicalmechanism operable, when actuated, to open and close said valve, thermalresponsive means on said pump for actuating said mechanical mechanism too en and close said valve, and means opera le in accordance with the iowof said cooling fluid for controlling said heating means for the pump.

2. In a vacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heatin means for said pump, meansfor circulating a cooling Huid around said pump, pipe connectionsincluding a valve between said chamber and said pump, mechanicalmechanism operable when actuated, to open and close said valve, andthermal responsive means on said pump for actuating said mechanicalmechanism to open and close said valve.

` 3. In avacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heating means for said pump, meansfor circulating a cooling fluid around said pump, pipe connections including a valve between said chamber and said pump, mechanical mechanismoperable, whenl actuated, to open and close said valve, and thermalresponsive means on said pump for actuating said mechanical mechanism toopen said valve.

time interval to` actuate ,said mechanicalv non-reversible'gearmechanism for opening said valve and holding it 1n o n position againstthe pressure of said yiel able means, and means for disconnecting saidnon-reversible gear mechanism from said valve to permit said yieldablemeans to close said valve.

6. In a vacuum-pumping system, the combination with a chamber to beevacuated, a pump, pipe connections including a valve between saidchamber and said pump, yieldablc means for closing said valve, a motorand non-reversible gear mechanism for opening said valve and holding itin open position against the (pressure of said yieldable means, meansfor isconnecting said non-reversible gear mechanism from said valve topermit said yieldable means to close said valve, means responsive toproper operating conditions of said pump to engage said gear mechanismand initiate the actuation of said motor, and means responsive to afailure or interruption of said pump to disengage said gear mechanism.

7 In a vacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heating means for said pump, meansfor circulating a cooling Huid around said pump, pipe connectionsincluding a valve between said chamber and said pump, yieldable meansfor closing said valve, a motor and non-reversible gear mechanism foropening said valve' and holding it in open position against the pressureof said yieldable means, means for disconnecting said non-reversiblegear mechanism from said valve to permit said yieldable means to closesaid valve, means responsive to the attainment of sufficiently hightemperatures in said pump to engage said gear mechanism and initiate theactuation of said motor, and means responsive to a failure orinterruption ofsaid pump to disengage said gear mechanlsm.

8. In a vacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heating means for said pump, meansfor circulating a cooling fluid around said pump, pipe connectionslncluding a valve between said chamber and said pump, yieldable meansfor closing said valve, a motor and non-reversible gear mechanism foropening said valve and holding it in open position against the ressureof said yieldable means, means or disconnecting said non-reversible gearmechanism from said valve to permit said yieldable means to close saidvalve, and thermal-responsive means on non-reversible gear mechanism foropening said valve and holding it 1n open position against the pressureof said yieldable means, and means for disconnecting said no1i-reversible gear mechanism from said valve to permit said yieldable means toclose said valve.

10. The combination with a valve, of quick-acting yieldable means foractuating said valve to one position, slow-acting means for actuatingsaid valve to another position and holding it against the pressure ofsaid yieldable means, said slow-acting means comprisingamotor andnon-reversible gear mechanism, and means for disconnecting saidnonreversible gear mechanism from said valve to permit said yieldablemeans to actuate the same.

11. A mechanically actuated valve mechanism characterized by having acam for pressing the valve to closed position, yieldable means formoving said cam in a valveclosin direction, a motor-actuatednon-reversib e gear mechanism for moving said cam in a valve-openingdirection against the pres# sure of said yieldable means and yforholding the same in said position, and means for uncoupling saidnon-reversible gear mechanism from said cam to permit the same to movein a valve-closing direction.

12. A mechanically actuated valve mechanism, characterized by having arotatably mounted segment having a cam surface of varying radii forpressing the valve to closed position, yieldable means for moving saidcam in a valve-closing direction, a worm-gear segment fixed to the camshaft, a driving shaft parallel to the cam shaft, a worm shaft dis osedat right angles to said driving shaft an carrying a worm, mea'ns forpivotally mountin said worm shaft with respect to said driving shaftwhereby said worm moves into and out of mesh with said worm-gearsegment, a mechanical connection between said shafts, and actuatingmechanism for pivotally moving said worm shaft.

13. A mechanically actuated valve meehanism, characterized by having arotatably mounted segment having a cam surface of varying radii forpressing the valve to closed position, yieldable means for moving saidcam in a valve-closing direction, a worm-gear segment fixed to the camshaft,a driving shaft parallel to the cam shaft, a-worm shaft disposedat right angles to said driving shaft and carrying a worm, means forpivotally mounting said worm shaft with respect to said driving shaftwhereby said worin moves int-o and out of mesh with said :worm-gearsegment, a mechanical connection between shaft being in such directionas to move sai cam in a valve-opening direction, an electromagnet forpivotally moving said worin shaft to engagement with said worm-gear seent, and a spring for pivotally movin sai worm shaft out of engagementwith sai worm-gear segment, the mounting of said spring being such thatthe movement of the cam in the valve-closing direction reduces thepressure exerted on the Worm shaft by said spring.

14. A mechanically actuated valve mechanism, characterized by having arotatably mounted segment having a cam surface of varying radii forpressing the valve to closed position, yieldable means for moving saidcam 1n a valve-closing direction, a Worm-gear se ment fixed to the camshaft, a driving sha t parallel to the cam shaft, a worin shaft disposedat right angles to said driving shaft and carrying a worm, means forpivotally mounting said worm shaft with respect to said driving shaftwhereby said worin moves into and out of mesh with said worm-gearsegment, a mechanical connection between said shafts, the driving actionof said driving shaft being in such direction as to move said cam in avalve-opening direction, an electromagnet forpivotally moving said wormshaft to engagement with said worm-gear segment, a spring for pivotallymoving said worm shaft out of engagement with said worm-gear segment,the mounting of said spring being such that the movement of the cam inthe valve-closing direction reduces the pressure exerted on the Wormshaft by said spring, means for simultaneously supplying driving powerto said driving shaft and energizing said electromagnet, an electriccircuit-interrupting means carried by said cam segment for stopping saiddriving shaft in the openvalve position of the cam, and means fordeenergizing said electromagnet whereby the valve is quickly closed bysaid yieldable means connected to said cam.

15. In a vacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heating means for said pump, meansfor circulating a cooling fluid around said pump, pi e connectionsincluding a valve between sai chamber and said pump, andfluid-presSure-responsive means in the path or circuit of said coolingfluid for controlling said heating means for the pump.

16. The combination with a machine to be cooled, of a source ofcooling-liquid supply, means including a liquid-flow-restricting feedingvalve for connecting said liquid-supply source to said machine, adischarge passage for the liquid leaving the machine, mechanism operablein accordance with the liquid flow disposed in said discharge passa andincluding -a movable diaphra which is movable inwardly and outwar ly inaccordance with changes in the said liquid-flow mechanism havin arestricted orifice through which the 1i uid ows and develops a pressurehead which 1s a small fraction of the pressure slightly beyond, saidcritical pressure for providing for a substantially unrestricted flow ofliquid through said mechanism, whereby said diaphragm 1s protected fromexcessive pressures. y y

17. In a vacuum-pumping system, the combination with a chamber to beevacuated, of a mercury-vapor pump, heating means for said pump, asource ot cooling-liquid supply, means including aliquid-tiow-restrxcting feeding valve for connecting said l1qu1d-supplysource to said pump, a discharge assage for the liquid leavingsaid pump,a mee anism operable in accordance with the liquid flow disposed in saiddischarge passage and 1ncluding a movable diaphragm which is movableinwardly and outwardly in accordance with changes in the liquid How,said mechanism having a restricted oriiice through .which the liquidflows and develops a ressurehead which is a small fraction o thepressure head which would be developed by the liquid-How through saidrestricted orifice if said feeding valve were opened wide, a controlmeans :for controlling the energization of said pump-heating means inaccordance with said liquid-How, said control means being operativelyassociated with said diaphragm to be operated by the outward movementthereof at a predetermined critical pressure developed by a desiredrestricted rate of flow, and a means operative at, or slightly beyond,said critical pressure for roviding for al substantially unrestricted owof 1i uid through said mechanism, whereby said iaphragm is protectedfrom excessive pressures.

18. A mechanism operable in accordance with liquid iow and including amovable diaphragm which is movable inwardly and outwardly in accordancewith changes in the liquid-flow, said mechanism havin a restrictedorifice through which the liquid flows and develops a pressure head, acontrol means actuated by the outward movement of said diaphragm at apredetermined critical pressure developed by a desired restricted rateof flow, and a means operative at, or slightly beyond, said criticalpressure for providing a substantially unrestricted How of liquidthrough said mechanism, whereby said da phragm is protected fromexcessive pressures.

In testimony whereof, I have hereunto sub scribed my name this 7th dayof July, 1927.

iiaaoL B. snare.

